Modern commercial aircraft may be fabricated using substantial amounts of composite materials, which require manufacturing apparatus and techniques different from those used with metal component production. Composite materials may be machine-placed or hand-applied. Automated fiber placement (AFP) machines were developed for the fabrication of large aircraft, with a typical AFP machine using a mandrel to place composite materials, usually as bundled composite fiber yarns, or tows, on the airframe. A typical AFP system uses an application head to align a plurality of independent composite tapes into contiguous edge contact, forming a single band, which subsequently is subjected to controlled placement onto the tool, or mandrel surface. AFP mandrels can be massive, often weighing from 20 tons to over 100 tons. AFP machines are most efficient when used in continuous rotation around the fuselage barrel; however, a typical airframe has numerous features for which continuous application techniques may be inefficient. Also, features such as cut-outs and openings for ports, hatches, doors, etc. may need one or more additional reinforcement layers of composite materials. Frequently, these layers are placed with an orientation or direction angle different from the primary orientation of continuous fiber placement. Currently, reinforcement materials may be supplied as unfinished composite panels, for example, an unfinished monolayer or multilayer prepreg fabric panel, or as a multilayer kit formed to approximately cover a region of airframe. During application, each panel may need to be cut, trimmed, bonded, and finished to accommodate underlying cut-outs and openings for ports, hatches, or doors.
During machine-placement of each reinforcement layer, a typical AFP mandrel may need to be stopped, repositioned, and restarted. For some applications, the steps of hand-application, trimming, bonding, and finishing, may be repeated numerous times. Manually-applied panels may be susceptible to errors inherent to piecemeal placement by human operators, including errors in positioning or application. With either method, an inspection may be performed after each layer is applied to ensure correct structural positioning, lamination and bonding integrity, and absence of undesirable characteristics, to within acceptable tolerances. A mis-positioned or misapplied panel may be removed from the fuselage and reapplied, or a new panel applied. Before reapplication, however, the underlying surface may need to be prepared again for panel application, thereby risking disturbance of, or damage to, that surface. In addition, the panel itself may be damaged during removal or reapplication.
Clearly, current processes used to apply composite materials, in such form, can be tedious, time-consuming, labor-intensive, and wasteful of materiel, increasing manufacturing costs and production time. Such inefficiencies can be unacceptable in the commercial production of large transport-class aircraft. As a result, there is a need for a layup kit and a method to manufacture such a kit that can be applied to an airframe efficiently, while minimizing both discontinuous AFP mandrel operation and manual layup application.